A leaf spring is made by bending a steel bar into a normally curved shape, and then heating it to temper the steel and impart the required springiness to it. To this end the steel blank is typically bent in a machine of the type described in the publication Blattfedern biegen und harten in automatischen Anlagen ("Leaf-spring bending and hardening in automatic machines" by Hans Hermann Kallenberg, special publication of Vogelverlag Wurzburg, 29th year, Baander, Bleche, Rohre, February 1989). This machine has holding jaws between which the normally straight spring blank is gripped and curved jaws that grip and bend the workpiece to the desired shape.
As a rule the jaws of the bender are removable so that the workpiece, or workpieces when two are bent at the same time, are taken out of the bender while still gripped by the jaws, and then the bent workpiece plus the jaws are passed through the heat-treatment bath. Only after the assembly is taken out of the treatment bath are the jaws opened up, separated from the tempered workpiece, and returned to the bending apparatus.
Thus with the known system it is necessary to provide a number of sets of bending jaws determined by the amount of time it takes to return a set of jaws to the bender dividied by the cycling time of the slowest step of the bending/hardening process. Since the bending jaws must be set up specially for the workpiece shape, this entails a consideragble amount of equipment and a considerable amount of time reconfiguring it each time workpiece shape changes.